Recently, semiconductor devices including capacitors using ferroelectrics or high dielectrics as the dielectric film are proposed. As a semiconductor device using a ferroelectric as the dielectric film of the capacitors, FeRAM (Ferroelectric Random Access Memory) is much noted. This ferroelectric memory is a nonvolatile memory characterized by high-speed operation, low electric power consumption, good write/read durability, etc. and is expected to be further developed.
However, when a ferroelectric or a high dielectric is used as the dielectric film, hydrogen or water often arrives at the capacitor dielectric film in steps following the formation of the dielectric film. When hydrogen or water arrives at the dielectric film, metal oxide forming the dielectric film is reduced with the hydrogen, which leads to the deterioration of the electric characteristics of the capacitors.
As techniques for preventing the deterioration of the dielectric film with hydrogen or water are proposed the technique of forming aluminum oxide film, covering the capacitors and the technique of forming aluminum oxide film on the inter-layer insulation film formed on the capacitors. Aluminum oxide film functions to prevent the diffusion of hydrogen or water. Accordingly, the proposed techniques can prevent the arrival of hydrogen or water at the dielectric film, and the deterioration of the dielectric film with hydrogen or water can be prevented.
Background art of the present application is as follows:
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